Casting machine with combined presser-band guide wheel

ABSTRACT

The invention disclosed is a combination presser-band guide wheel for guiding an endless flexible band into closed relationship with a portion of the peripheral groove of a rotatable casting wheel. The presser-guide wheel is positioned adjacent the periphery of the rotatable casting wheel on a pivot arm and is arranged to press a flexible band into positive contact with the casting wheel at or near the point where molten metal first contacts the casting wheel.

United States Patent [1 1 3,811,492 Ward May 21, 1974 CASTING MACHINE WITH COMBINED 3,596,702 8/1971 Ward et a1. 164/87 PRESSER.BAND GUIDE WHEEL 3,318,364 5/1967 Bray et a1. 164/278 X 3,326,271 6/1967 Cofer 164/278 [75] Inventor: George C. Ward, Carrollton, Ga.

[73] Assignee: Southwlre Company, Carrollton,

[22] Filed: May 8, 1972 [21] Appl. No.: 251,208

[52] US. Cl. 164/278, 164/87 [51] Int. Cl 1322d 11/06 [58] Field of Search 164/87, 276278 [56] 3 References Cited UNITED STATES PATENTS 1,612,737 12/1926 Lane 164/278 3,406,739 10/1968 Brand 164/278 3,455,371 7/1969 Nichols et al 1'64/87 Primary Examiner-R. Spencer Annear Attorney, Agent, or Firm-Herbert M. Hanegan; Van C. Wilks 5 7] ABSTRACT The invention disclosed is a combination presser-band guide wheel for guiding an endless flexible band into closed relationship with a portion of the peripheral groove of a rotatable casting wheel. The presser-guide wheel is positioned adjacent the periphery of the rotatable casting wheel on a pivot arm and is arranged to press a flexible band into positive contact with the casting wheel at or near the point where molten metal first contacts the casting wheel.

4 Claims, 3 Drawing Figures Tan/Alec 774/6 MIENTEUIAY 2 1 m4 SHEET 2 OF 3 CASTING MACHINE WITH COMBINED PRESSER-BAND GUIDE WHEEL BACKGROUND OF THE INVENTION In a typical system for continuously casting metal, such as copper, steel, aluminum or the like, an endless flexible metal band is guided about a portion of the peripheral groove of a rotatable casting wheel, and molten metal is poured into the moving mold formed by the band and the peripheral groove in the casting wheel. As the casting wheel rotates, coolant is applied to its external surfaces and to the outside surface of the portion of the band that closes the peripheral groove of the casting wheel to extract the heat from the molten metal at a rapid rate and to prevent the casting wheel and band from overheating. By the time the metal band is removed from the peripheral groove of the casting wheel by the band guide wheels, the molten metal will have been solidified and can be extracted from the casting wheel and passed on to another stage in the continuous process.

The function of the band guide wheels is to guide the band into engagement with the periphery of the casting wheel to form an arcuate mold, and then to remove the band from the periphery of the casting wheel to open the mold, and guide the band back to its initial mold forming position. One arrangement is to have a single large tensioning wheel spaced above the casting wheel and have the inner surface of the flexible band extend about both the casting wheel and the tensioning wheel. The other typical arrangement is to have the band pass beneath the casting wheel during its return flights, with the casting wheel engaging the inner surface of the band and the band guide wheels engaging the outer surface of the band. In both arrangements it is desirable to guide the band away from the area above the casting wheel so that the equipment necessary for pouring the molten metal into the mold and extracting the solidified metal from the mold can be positioned in this space. Thus the tensioning wheel and band guide wheels must be sized and positioned to guide the band away from the upper portion of the casting wheel; however, in prior art casting systems in order that the band be guided away from the upper portion of the casting wheel, it had been found necessary to utilize a relatively small band presser wheel (band positioning wheel) to position the band adjacent the casting wheel and urge the band into its initial engagement with the periphery of the casting wheel. The band positioning wheel was of small diameter in order to keep the area above the casting wheel relatively free from encumbrance by the band.

In the operation of a continuous casting machine of the types generally set forth above, one of the major maintenance problems is the care and replacement of the band. It is necessary that the band be of relatively small thickness so that it can bend and flex as it passes around the casting wheel and band guide wheels. Also, a relatively thin band transfers the heat from the molten metal more rapidly than a thicker band and allows the molten metal to solidify more rapidly; however, a relatively thin band is more likely to become overheated from the transfer of heat from the molten metal and deteriorate more rapidly than a thicker band. Thus, the endless flexible metal band utilized with a continuous metal casting machine must be fabricated with a thickness to withstand substantial heat deterioration, and yet be thin enough to flex around the band wheels. The continual bending and flexing of the band about the smaller band positioning wheel had a most damaging effect on the band since the band was required to undergo a curvature of a shorter radius when passing around this wheel, and the strain exerted on the band from the smaller band wheel tended to rapidly deteriorate the band.

SUMMARY OF THE INVENTION Briefly described, the present invention comprises a casting machine for continuously casting metal which, due to the combination of the presser wheel and a band guide wheel, extends the life of the band. The positioning wheel next adjacent the casting wheel which urges the band into engagement with the casting wheel at or near the pouring spout has been enlarged so that the strain experienced at this location is not significantly more than the strain experienced at the band guide wheels. To enlarge the positioning wheel, more space to the side of the casting wheel was required because the top had to be kept open for metal handling equipment. More space and a larger positioning wheel were achieved by combining a band guide wheel with the presser wheel, thereby eliminating the band guide wheel configuration adjacent the casting wheel nearest the position where the band and the peripheral groove first form an arcuate mold. This configuration increases the sealing ability of the band at the point of first contact with the casting wheel. The invention increases contact pressure whenever band tension is increased, thereby increasing the consistency and quality of the cast metal.

Thus, it is an object of this'invention to provide a casting machine for continuously casting metal which includes a band and band wheel arrangement that extends the life of the band.

Another object of this invention is to provide a casting machine for continuously casting metal that requires less maintenance than required by prior art casting machines.

A further object of this invention is to eliminate spills of metal from the casting wheel mold due to imperfect fitting or lack of pressure by the band.

Other objects, features and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a casting machine for continuously casting metal wherein the inner surface of the band is passed around the casting wheel, and the outer surface of the band is engaged by a pivotally mounted combined presser-band guide wheel and three band guide wheels.

FIG. 2 is a schematic illustration of a prior art casting machine for continuously casting metal wherein the inner surface of the band is passed around the casting wheel and the outer surface is engaged by four large band guide wheels and a smaller band positioning wheel.

FIG. 3 is a schematic illustration of the prior art casting machine of FIG. 2 showing the band under increased tension.

DESCRIPTION OF THE PREFERRED.

EMBODIMENTS Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, FIG. 1 shows casting wheel 11 engaged by band 12 to form an annular mold cavity (not shown). Pour spout 26 is positioned above casting wheel 11 such that molten metal pours into the annular mold cavity formed by casting wheel 11 and band 12 near point 16. Presser-band guide wheel 14 is mounted for rotation on pivot and 15 about pivot point 25. Conventional means for moving pivot arm 15 away from casting wheel 11, thereby decreasing tension in band 12 and lessening the contact between band 12 and casting wheel 11 at point 16, and for moving pivot arm 15 toward casting wheel 1 1, thereby increasing the tension in band 12 and pressing band 12 into closercontact with casting wheel 11 at point 16 are contained in the casting machine behind pivot point 25. Such conventional means arev illustrated schematically in FIG. 1 as including a motive source 30 and a connecting arm 31. Band 12 is further supported by band guide wheels 17, 18 and 19 and travels in a counterclockwise direction, i.e., around casting wheel 11 in the direction of guide wheel 17, then around guide wheels 17, 18, 19 and presser-band guide wheel 14. As band 12 tension is increased, presser-band guide wheel 14 is moved into I tighter contact with casting wheel 11 at point 16. Variable pressure is applied at point 16 by adjusting the tension on band 12, thereby lessening air contact with the molten metal entering the annular mold cavity at or prior to point 16.

The advantages of having a combined presser-band guide wheel can be demonstrated by comparing FIG. 1 with FIG. 2 and FIG. 3. As noted above in FIG. 1, band tension tends to hold presser-band guide 14 in close contact with casting wheel 11. Whereas in FIGS. 2 and 3 increasing tension on band 12 tends to move presser wheel 20 away from casting wheel 11, thereby tending to create a greater possibility for air to contact the molten metal that enters the mold cavity at or prior to point 16.

The present invention combines a band guide wheel with a presser wheel, thereby providing the advantage of variable pressure at point 16 plus the advantage of having only one wheel. The single wheel configuration reduces band 12 flexing by eliminating one small wheel (i.e., presser wheel 20 shown in FIGS. 2 and 3) and one turn, thereby increasing the life of the band. The FIG. 1 configuration further allows reduced maintainance and operator attention by insuring closed contact between casting wheel 11 and band 12 due to band tension at point 16, thereby freeing the operator from constantly monitoring for correct contact of band and wheel at point 16.v

FIG. 2 depicts the prior art design of continuous casting equipment which utilizes a casting mold cavity formed by forcing continuous band 12 into intimate contact with casting wheel 11. Band 12 performs the function of closing the cavity to form a closed annular mold. In the prior art design, band 12 is forced into contact with casting wheel 11 by presser wheel 20. Band 12 is supported by fixed band guide wheels 21, 22, 23, and 24. One of the disadvantages of this design is that stress is induced in band 12 by virture of the size and method of operation of presser wheel 20. A wheel of limited size is dictated by the location of the presser wheel between band guide wheel 21 and casting wheel 11. The small size of presser wheel 20 results in undesirable working of the band 12.

A further disadvantage of prior'art designs is that as band tension is increased in order to achieve closer contact between band 12 and casting wheel 11, band 12 attempts to assume the path of least resistance to minimize stress in the band. Presser wheel 20 attempts to restrain band 12 and is subject to being lifted, as shown in FIG. 3, if sufficient force is not applied to the presser wheel to overcome the band force. This tendency to lift from contact with the mold has a detrimental effect on the casting process. If presser wheel 20 does not maintain adequate contact betweenband 12 and casting wheel 11, the mold cavity will be overfilled and fins will be formed on the cast section. These fins result in a poor quality product when the cast material subsequently is processed to its final form.

Also when presser wheel 20 is lifted, decreasing contact between band 12 and casting wheel 11, the molten metal being poured into the casting wheel is subject'to greater exposure to the atmosphere which results in'a poor quality product because of the increased rate of reaction between the atmosphere and the molten metal at the elevated pouring temperature.

FIG. 1 shows the disclosed invention wherein a band guide wheel has been combined with the presser wheel to produce presser-band guide wheel 14. Thiscombination of the presser and band guide wheels into one unit results in several advantages. One advantage is that due to the larger size of this unit when compared to the prior art (presser-band guide wheel 14 has a-diameter which is no less that substantially the diameter of r a band guide wheel) bandl2 undergoes less working. Replacing the presser and band guide wheels with one wheel eliminates one bend of band 12, thereby further decreasing working of the band. A further advantage of presser-band guide wheel 14 is that the sealing effect at point 16 is increased when band tension is increased, and is not diminished as in prior art designs. Presserband guide wheel 14 is mounted on pivot arm 15, which operates within an arc of movement offset from the vertical position in the direction of casting wheel 11. In other words, as seen in FIG. 1, the pivot arm 15 always extends to the left of a vertical line extending through the pivot point 25. The effect of the operating position of the presser-band guide wheel is to increase the sealing effect at point 16 whenever band tension is increased. Pulling band 12 more tightly about casting wheel 11 causes the presser-band guide wheel to be drawn more tightly against the casting wheel as the band seeks the position of least strain. This self sealing effect of the presser-band guide wheel results in cast material with few or no fins. The avoidance of the necessity for operator attention to presser-band guide wheel adjustment is another advantage of this design. In prior art designs operator adjustment was necessary to offset the lifting force on the presser wheel produced by increased band tension, however the self sealing effect of the present invention makes operator atten tion unnecessary.

It will be obvious to those skilled in the art that many variations may be made in the embodiments chosen for the purpose of illustrating the present invention without departing from the scope thereof as defined by the appended claims.

What is claimed is:

1. In a casting machine having a mold formed by a rtatable casting wheel with a peripheral groove and by an endless band which engages the periphery of said casting wheel, a plurality of band guide wheels of substantially the same diameter fixedly mounted for rotation adjacent the periphery of said casting wheel to remove said band from the surface of said casting wheel and to redirect said band toward its mold forming position on said casting wheel, band positioning and tensioning means for selectively positioning and tensioning said band at a predetermined point of contact on the peripheral surface of said casting wheel, said band positioning and tensioning means including a wheel having a diameter which is no less than substantially the diameter of a band guide wheel for urging said band into various contact points with the periphery of said casting wheel, said band positioning and tensioning means being pivotally mounted for rotation toward and away from the periphery of said casting wheel, means for rotating said band positioning and tensioning means into a position of closer proximity to said casting wheel thereby increasing tension in said band and varying the point of contact, said band positioning and tensioning means being mounted on a pivot arm having an axis of rotation extending substantially parallel to the axis of rotation of the casting wheel, and wherein said means for rotating said band positioning and tensioning means acts through said pivot arm.

2. The casting machine of claim 1 having no more than three band guide wheels rotatably mounted adjacent the periphery of said casting wheel.

3. The casting machine of claim 1 wherein said pivot arm is inclined in the direction of said casting wheel.

4. The casting machine of claim 1 wherein increases of tension in said band cause said positioning and tensioning means to be drawn more tightly against said casting wheel in a self-sealing manner. 

2. The casting machine of claim 1 having no more than three band guide wheels rotatably mounteD adjacent the periphery of said casting wheel.
 3. The casting machine of claim 1 wherein said pivot arm is inclined in the direction of said casting wheel.
 4. The casting machine of claim 1 wherein increases of tension in said band cause said positioning and tensioning means to be drawn more tightly against said casting wheel in a self-sealing manner. 